1. Field of the Invention
This invention relates to security systems and, more particularly, to latching arrangements for power driven gates used in secured areas.
2. Description of the Prior Art
The use of security gates has been steadily increasing in applications such as subterranean garages for apartments or condominiums and as a means for controlling access into secured storage rental areas, since the use of such gates is substantially cheaper than the cost of hiring a security guard for round-the-clock protection against theft and vandalism. Such security gates are sturdily constructed of heavy iron or steel bars, and are driven on metal tracks by an electric drive system actuated by either a remote control unit or by a stationary electric input unit, such as a keyed switch or a key pad into which a predetermined code must be entered to gain access. By requiring either possession of an appropriately-coded remote control unit, a key or knowledge of an entry code, access to the garage or rental areas may be limited to minimize the possibility of unauthorized entry, theft, or vandalism.
The security gate is typically driven by a chain drive extending between a gear-reduction electric motor drive and the gate, typically with one or more idler wheels mounted on a fixed portion of the wall or fence adjacent the security gate. While such security systems operate efficiently and cheaply and are effective in limiting unauthorized entry to the secured area, they offer a barrier which may usually be circumvented in seconds by a professional criminal. By placing a sufficient amount of pressure on most closed security gates, the gate will either yield with moderate difficulty, or resist until the weakest component in the system, usually the chain used to drive the gate, fails by snapping, thus allowing the gate to slide smoothly open.
In order to prevent security gates from being forced open, some type of mechanical latching device which securely latches when the gate is closed, and which will only unlatch when the unlocking signal is received by the system is required. Such a latching system must be highly resistant to attempts to force the security gate open. The latching device must also open quickly and smoothly, and minimize the amount of failures requiring trained repair personnel to correct.
One such device is an electromagnetic solenoid-driven bolt device, which is mounted on a portion of the security gate inaccessible from outside the secured area. The bolt is provided with a reinforced metal aperture into which to slide, the aperture being mounted on the wall or floor of the secured location. When the electromagnetic solenoid is deactivated, the bolt automatically moves into the aperture, completely preventing movement of the gate until the solenoid is activated again.
Although the electromagnetically-driven solenoid-actuated bolt latching device works quite well on initial installation, it has a number of significant problems. The first problem is that wear, damage from use, or a poor fit from a faulty installation may result in failure of the bolt to be driven electromagnetically out of the aperture upon activation of the solenoid. Since it is quickly recognized that such solenoids may provide only a limited amount of force, there is a persistent problem in such devices presented by the bolts sticking in the aperture due to one of the aforesaid reasons, preventing the security gate from being opened when desired.
A second problem with the electromagnetically-driven solenoid-actuated latch is that, since the device is driven by electricity, there must necessarily be an electrical link between the solenoid assembly mounted on the gate and the fixed components of the system mounted within the secured area. Such an electrical link is difficult to arrange in an economical installation, and is also subject to a substantially higher than acceptable failure rate. A major disadvantage of the electromagnetic solenoid latching device is the simple fact that such a system is quite expensive to manufacture and to install, particularly if the system is to be constructed to minimize the above-described mechanical disadvantages. The high cost of purchase and installation effectively prevents installation of a latching system on security gates in all but the largest apartment or condominium complexes, or storage rental areas. It can thus be appreciated that there is a substantial need for a reliable, simple latching device to control access to areas protected by a security gate.